JP6020008B2 - Brake system for vehicles - Google Patents

Description

  The present invention generates a braking force for a vehicle by performing coordinated control of a hydraulic brake device that generates a hydraulic braking force using brake fluid and a regenerative brake device that generates a regenerative braking force using a motor or the like. The present invention relates to a vehicle brake system.

  Conventionally, brake fluid is sucked from a master cylinder (hereinafter referred to as M / C) by driving a pump provided in a hydraulic brake device, and wheel cylinders (hereinafter referred to as W / C) provided in each wheel. A so-called in-line system has been proposed in which a hydraulic braking force is generated on a wheel by discharging the gas (for example, see Patent Document 1).

  The hydraulic brake device of this in-line system is also applied to a vehicle brake system that generates a target braking force by performing coordinated control of the hydraulic braking force generated by the hydraulic brake device and the regenerative braking force generated by the regenerative braking device. Has been applied. For example, in a vehicle brake system equipped with a hydraulic brake device and a regenerative brake device, the regenerative brake device generates a regenerative braking force corresponding to the brake operation state, but the region where the regenerative braking force cannot be generated and the vehicle speed are Regenerative cooperative control of the hydraulic braking force and the regenerative braking force is performed to generate a desired target braking force by generating a hydraulic braking force by driving the pump in a low region.

JP 2009-90946 A

  However, in the in-line system, when the brake pedal is depressed beyond the position where the port connecting the M / C and the master reservoir is blocked, the brake fluid is sucked in from the M / C by driving the pump. When / C is pressurized, the M / C pressure decreases due to the inhalation of brake fluid from within the M / C, the pedal reaction force decreases, and the brake pedal is sucked into the M / C side, resulting in worse brake feeling. The problem occurs.

  For example, in a vehicle brake system in which regenerative cooperative control is performed, a hydraulic braking force and a regenerative braking force are switched. That is, when the vehicle speed becomes low and the regenerative braking force decreases, replacement is performed to increase the hydraulic braking force by increasing the W / C pressure to compensate for this. The above problem occurs when such replacement is performed.

  There are various types of vehicle brake systems in which regenerative cooperative control is performed, but the above-described problem can occur with any type of brake system.

  For example, in a vehicle brake system in which regenerative cooperative control is performed, a regenerative port may be provided separately from a normal port as a port connecting an M / C and a master reservoir, but a predetermined deceleration occurs. To the extent, the regenerative port is not blocked by the master piston, and play is provided so that the hydraulic braking force based on the M / C pressure is not generated. Even in such a case, if the brake pedal is depressed more than the regenerative port is blocked, the above problem occurs because the brake fluid in the M / C is sucked.

  In addition, the hydraulic brake device is provided with a stroke simulator so that a normal pedal feeling can be obtained during regenerative braking so that a desired stroke characteristic (stroke amount of the brake pedal-depression force characteristic) can be obtained. is there. Even in this case, since the hydraulic braking force is generated by driving the pump in a region where the regenerative braking force is not generated or a region where the vehicle speed is low, the above problem occurs.

  In view of the above, the present invention provides a vehicle brake system that can prevent deterioration of brake feeling caused by a brake operation member (for example, a brake pedal) being sucked into the M / C side by inhalation of brake fluid from the M / C. The purpose is to provide.

In order to achieve the above object, according to the first aspect of the present invention, the brake fluid in the M / C is controlled by controlling at least one of the pump and the differential pressure control valve by the braking force control means while the port is closed. Is being supplied into the W / C, the suction operation state in which the suction of the brake operation member to the M / C side is generated by the supply of the brake fluid, and the predicted suction state in which the suction is expected to occur Increase the amount of brake fluid supplied from the M / C to the W / C per unit time so that the master piston is tilted down when the state is at least one of the states. The brake fluid supply amount control means (100 to 170) for executing the brake fluid supply amount increase control is provided.

  As described above, when each port is closed, when brake fluid is sucked from the M / C by pump drive and supplied to the W / C to pressurize the W / C, the brake fluid supply amount increase control is performed. ing. In other words, when it is at least one of the suction occurrence state where the suction of the brake operation member is generated and the suction prediction state where the suction is expected to be generated, compared with the case where it is not the state, The supply amount of brake fluid is increased. As a result, the master piston (13a, 13b) is caused to fall down, and the sealing force between the master piston and the inner wall surface of each chamber (13c, 13d) can be reduced. Brake fluid can be sucked from the side. For this reason, it can suppress that a brake operation member is sucked into the M / C side, and it can prevent deterioration of brake feeling.

  In the invention according to claim 2, the braking force control means pumps the regenerative braking force generated by the regenerative braking device by increasing the hydraulic braking force in response to a decrease in the regenerative braking force during braking. The brake fluid supply amount control means executes at least one of the differential pressure control valve and the pump when the replacement processing is being performed. It is characterized by determining that the brake fluid in the master cylinder is supplied into the wheel cylinder by the above control.

  As an example of control in which brake fluid is sucked from within the M / C, that is, control in which brake fluid in the M / C is supplied into the W / C by control of at least one of the pump and the differential pressure control valve A replacement process from a regenerative braking force to a hydraulic braking force can be mentioned. During this replacement process, it is assumed that the suction operation state where the suction of the brake operation member has occurred, or the suction prediction state where the occurrence of suction is expected, the brake fluid is compared with the case where it is not in these states. The effect described in claim 1 can be obtained by increasing the supply amount.

  According to a third aspect of the present invention, the brake fluid supply amount control means increases the amount of increase in the differential pressure per unit time of the differential pressure by the differential pressure control valve in the brake fluid supply amount increase control.

  As described above, in the brake fluid supply increase control, by increasing the differential pressure increase per unit time of the differential pressure by the differential pressure control valve, for example, by increasing the differential pressure indicated by the differential pressure command value, the differential pressure is reduced. The pressure difference can be increased from the small state, and the brake fluid can be easily sucked and discharged by the pump. As a result, the amount of brake fluid supplied is increased in the suction occurrence state where the brake operation member is sucked or in the suction prediction state where the suction is expected to occur, compared to the case where the suction is not expected. Can be made.

  The invention according to claim 4 is characterized in that the brake fluid supply amount control means determines that it is in a suction predicted state when the master cylinder pressure is equal to or lower than a predetermined pressure (Pm1).

  As described above, when the generated M / C pressure becomes equal to or lower than the predetermined pressure, that is, when the M / C pressure is reduced to the extent that the suction of the brake operation member is expected to occur, the suction prediction state is established. Thus, the brake fluid supply amount increase control is performed. Thereby, generation | occurrence | production of the suction of a brake operation member can be suppressed from earlier.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

It is the figure which showed the block structure of each function of the hybrid vehicle by which the vehicle brake system 1 in 1st Embodiment of this invention is mounted. It is the figure which showed the detailed structure of each part which comprises a hydraulic brake device. It is sectional drawing which showed the mode in M / C13. 5 is a flowchart showing details of a brake fluid supply amount increase control executed by a brake ECU 70. It is a time chart when brake fluid supply amount increase control is performed when a brake operation is performed to such an extent that a relatively high deceleration (high G) is generated. It is a time chart when the brake fluid supply amount increase control is executed when the brake operation is performed to such an extent that a relatively low deceleration (low G) is generated.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 shows a block configuration of each function of a hybrid vehicle equipped with a vehicle brake system 1 including a hydraulic brake device and a regenerative brake device to which the first embodiment of the present invention is applied.

  First, the hydraulic brake device provided in the vehicle brake system 1 of the present embodiment will be described. As shown in FIG. 1, the vehicle brake system 1 includes a brake pedal 11, a booster 12, an M / C 13, W / C 14, 15, 34, and 35, and a brake fluid pressure control actuator 50. The hydraulic brake device of the in-line system is constituted by these. The vehicle brake system 1 includes a brake ECU 70. The brake ECU 70 functions as part of a portion that executes regenerative cooperative control for coordinating the hydraulic braking force generated by the hydraulic brake device with the regenerative braking force generated by the regenerative brake device. FIG. 2 is a diagram showing a detailed structure of each part constituting the hydraulic brake device.

  As shown in FIG. 2, a stroke sensor 11 a is connected to a brake pedal 11 as a brake operation member that is depressed by a driver, and a detection signal from the stroke sensor 11 a is transmitted to the brake ECU 70. 11 stepping amount (operation amount) is detected. Moreover, the brake pedal 11 is connected to the booster 12 and the M / C 13, and when the driver depresses the brake pedal 11, the pedaling force is boosted by the booster 12 and is disposed in the M / C 13. The master pistons 13a and 13b are pressed. As a result, the same M / C pressure is generated in the primary chamber 13c and the secondary chamber 13d defined by the master pistons 13a and 13b. The M / C pressure generated in the M / C 13 is transmitted to each of the W / Cs 14, 15, 34, and 35 through the brake fluid pressure control actuator 50 constituting the fluid pressure path.

  The M / C 13 is connected to a master reservoir 13e having a passage communicating with the primary chamber 13c and the secondary chamber 13d. The master reservoir 13e supplies brake fluid into the M / C 13 and stores excess brake fluid in the M / C 13.

  Specifically, the master reservoir 13e is connected on the secondary chamber 13d side of the normal port 13f in the primary chamber 13c in addition to the normal ports 13f and 13g connected to the primary chamber 13c and the secondary chamber 13d of the M / C 13, respectively. It is connected to the inside of the M / C 13 through the regenerative port 13h. The normal ports 13f and 13g are blocked by the master pistons 13a and 13b when the master pistons 13a and 13b move by the same stroke amount, and the brake fluid flows between the M / C 13 and the master reservoir 13e through the ports 13f and 13g. However, the regenerative port 13h has a brake fluid between the primary chamber 13c and the master reservoir 13e until the master piston 13a is further stroked and blocked by the master piston 13a even after the normal port 13f is blocked. Allowed to flow. The regenerative port 13h is arranged based on the relationship with the maximum regenerative braking force that can be generated by the regenerative braking device. For example, since the M / C pressure is not generated until the regenerative port 13h is blocked by the master piston 13a, the maximum regenerative braking force is already generated by the regenerative brake device when the master piston 13a strokes and closes the regenerative port 13h. The distance from the initial position of the master piston 13a to the regenerative port 13h is set so as to be in a generated state.

  As described above, since the same master pressure is generated in the primary chamber 13c and the secondary chamber 13d, until the regenerative port 13h is blocked by the master piston 13a, the primary chamber 13c and the secondary chamber 13d The M / C pressure generated at 0 is zero.

  The brake fluid pressure control actuator 50 includes a first piping system 50a and a second piping system 50b. The first piping system 50a controls the brake fluid pressure applied to the left rear wheel RL and the right rear wheel RR, and the second piping system 50b controls the brake fluid pressure applied to the left front wheel FL and the right front wheel FR. The front and rear pipes are constituted by the two piping systems of the first and second piping systems 50a and 50b.

  Hereinafter, the first and second piping systems 50a and 50b will be described. However, since the first piping system 50a and the second piping system 50b have substantially the same configuration, the first piping system 50a will be described here. For the second piping system 50b, refer to the first piping system 50a.

  The first piping system 50a is provided with a pipeline A serving as a main pipeline that transmits the above-described M / C pressure to the W / C 14 provided in the left rear wheel RL and the W / C 15 provided in the right rear wheel RR. It has been. Through this line A, W / C pressure is generated in each of the W / Cs 14 and 15.

  Further, the pipe line A is provided with a first differential pressure control valve 16 including a pressure regulating valve that can be controlled between a communication state and a differential pressure state. The first differential pressure control valve 16 is in a communicating state in the normal brake state, and is in a differential pressure state when a current is passed through the solenoid. The differential pressure formed by the first differential pressure control valve 16 changes according to the differential pressure command value (current value of the current flowing through the solenoid), and the larger the differential pressure command value, the greater the differential pressure. When the first differential pressure control valve 16 is in the differential pressure state, the flow of the brake fluid is regulated so that the W / C pressure is higher than the M / C pressure by the amount of the differential pressure.

  The pipe A branches into two pipes A1 and A2 downstream of the first differential pressure control valve 16 on the W / C 14 and 15 side. One of the two pipes A1 and A2 is provided with a first pressure increase control valve 17 for controlling the increase of the brake fluid pressure to the W / C 14, and the other is an increase of the brake fluid pressure to the W / C 15. A second pressure increase control valve 18 is provided for controlling the pressure.

  The first and second pressure increase control valves 17 and 18 are configured as electromagnetic valves as two-position valves that can control the communication / blocking state. When the first and second pressure-increasing control valves 17 and 18 are controlled to be in a communicating state, the M / C pressure or the brake fluid pressure due to the discharge of brake fluid from a pump 19 described later is applied to the W / C 14 and 15. .

  During normal braking by the driver operating the brake pedal 11, the first differential pressure control valve 16 and the first and second pressure increase control valves 17 and 18 are constantly controlled. The first differential pressure control valve 16 and the first and second pressure increase control valves 17 and 18 are provided with safety valves 16a, 17a and 18a, respectively, in parallel.

  In the pipeline A, the first and second pressure-increasing control valves 17 and 18 and the pipeline B serving as a pressure-reducing pipeline connecting between the W / Cs 14 and 15 and the pressure regulating reservoir 20 are controlled in the communication / blocking state. As a two-position valve that can be formed, a first pressure reduction control valve 21 and a second pressure reduction control valve 22 each comprising an electromagnetic valve are provided. These first and second pressure reducing control valves 21 and 22 are always cut off during normal braking.

  A conduit C serving as a reflux conduit is disposed so as to connect between the pressure regulating reservoir 20 and the conduit A. This pipe C is provided with a self-priming pump 19 driven by a motor 60 so as to suck and discharge brake fluid from the pressure regulating reservoir 20 toward the M / C 13 side or the W / C 14, 15 side. Yes. The discharge port side of the pump 19 is provided with a safety valve 19a so that high-pressure brake fluid is not applied to the pump 19, and a fixed capacity for relaxing the pulsation of the brake fluid discharged by the pump 19. A damper 23 is provided.

  And the pipe line D used as an auxiliary pipe line is provided so that the pressure regulation reservoir 20 and M / C13 may be connected. Through this pipe D, the pump 19 sucks brake fluid from the M / C 13 and discharges it to the pipe A, so that the traction control or anti-lock brake control can be performed regardless of the operation of the brake pedal 11 by the driver. The brake fluid can be supplied to the W / C 14 and 15 side to increase the W / C pressure of the target wheel. The pressure regulating reservoir 20 is configured such that when a predetermined amount of brake fluid is stored, the pressure regulating valve is shut off so that the brake fluid is not sucked. Therefore, more brake fluid than the suction capacity of the pump 19 does not flow into the pressure regulating reservoir 20, and no high pressure is applied to the suction side of the pump 19.

  The brake fluid pressure control actuator 50 is provided with an M / C pressure sensor 51. The M / C pressure sensor 51 is provided in a portion of the brake pipe that has the same pressure as the M / C pressure. In the present embodiment, the M / C pressure sensor 51 and the first differential pressure in the pipe A A control valve 16 is provided. A detection signal of the M / C pressure sensor 51 is transmitted to the brake ECU 70.

  On the other hand, as described above, the second piping system 50b has substantially the same configuration as the first piping system 50a. That is, the first differential pressure control valve 16 and the safety valve 16a correspond to the second differential pressure control valve 36 and the safety valve 36a. The first and second pressure increase control valves 17 and 18 and the safety valves 17a and 18a correspond to the third and fourth pressure increase control valves 37 and 38 and the safety valves 37a and 38a, respectively. , 22 correspond to the third and fourth decompression control valves 41, 42, respectively. The pressure regulation reservoir 20 corresponds to the pressure regulation reservoir 40. The pump 19 and the safety valve 19a correspond to the pump 39 and the safety valve 39a. The damper 23 corresponds to the damper 43. Further, the pipeline A, the pipeline B, the pipeline C, and the pipeline D correspond to the pipeline E, the pipeline F, the pipeline G, and the pipeline H, respectively. As described above, the hydraulic brake device in the vehicle brake system 1 is configured. By controlling the hydraulic brake device by the brake ECU 70, a hydraulic braking force based on cooperative control with the regenerative braking force by the regenerative braking device is generated.

  The brake ECU 70 is configured by a known microcomputer including a CPU, a ROM, a RAM, an I / O, and the like, and executes processing such as various calculations according to a program stored in the ROM. For example, the brake ECU 70 receives a detection signal from a wheel speed sensor (not shown) that detects the wheel speed to obtain the wheel speed, obtains the vehicle speed (estimated vehicle body speed) from the wheel speed, and detects the vehicle speed (estimated vehicle body speed) or the M / C pressure. Based on the detection signal of the sensor 51, the stroke value of the brake pedal 11 and the M / C pressure are obtained. Based on the electrical signal from the brake ECU 70, the control valves 16-18, 21, 22, 36-38, 41, 42 and the motor 60 for driving the pump are controlled to adjust the hydraulic braking force by the hydraulic brake device. Is done.

  Specifically, each control valve 16-18, 21, 22, 36-38, 41, 42 is driven based on an electrical signal from the brake ECU 70, and each control valve 16-18, 21, 22, 36-38. , 41, and 42, the brake fluid pressure corresponding to the driving state is generated in the W / Cs 14, 15, 34, and 35, so that the braking force generated in each wheel is controlled.

  For example, when the hydraulic braking force is generated for the front wheels FL and FR, the motor 60 is driven with the second differential pressure control valve 36 in the differential pressure state, and the pump 39 sucks and discharges the brake fluid. As a result, the brake fluid in the M / C 13 is sucked into the pump 39 through the pipes H and G, and is supplied to the W / Cs 34 and 35 of the front wheels FL and FR through the pipes G and E. Further, the differential pressure instruction value of the second differential pressure control valve 36 is set according to the cooperation with the regenerative braking force, and the differential pressure according to the cooperation with the regenerative braking force is generated at the second differential pressure control valve 36. Thereby, W / C34, 35 can be pressurized based on the differential pressure according to cooperation with regenerative braking power, and hydraulic braking power based on cooperative control with regenerative braking power by a regenerative brake device can be generated.

  Next, the regenerative braking device provided in the vehicle brake system 1 of the present embodiment will be described. As shown in FIG. 1, the hybrid vehicle includes a regenerative brake device and a hybrid ECU 80 that controls the regenerative brake device.

  The regenerative braking device includes a motor 81 connected to an axle that connects both front wheels FL and FR, an inverter 82 electrically connected to the motor 81, a battery 83 electrically connected to the inverter 82, and the like. It is said that. The motor 81 is configured, for example, as an AC synchronous type, and power is supplied to the motor 81 by converting a DC current generated by the battery 83 by the inverter 82 into an AC current. The inverter 82 plays a role of converting a direct current of the battery into an alternating current based on a control signal of the hybrid ECU 80 and a role of charging the battery 83 by converting the alternating current generated by the motor 81 into direct current.

  The hybrid ECU 80 mainly controls the drive system, but supplies data used for regenerative brake control to the brake ECU 70 and receives necessary data from the brake ECU 70. The hybrid ECU 80 performs regenerative braking control in cooperation with the brake ECU 70, and controls the inverter 82 to control the operation of the motor 81 and the charging of the battery 83. Specifically, the operation of the motor 81 is controlled by the inverter 82 based on the control signal of the hybrid ECU 80, and the motor 81 is driven by the rotational force of both front wheels FL, FR (or the axle connecting them) to generate power. The battery 83 is charged with the electric power thus obtained. Since the braking force is generated by the resistance force of the motor 81 during power generation, this is used as the regenerative braking force.

  The hybrid ECU 80 handles various types of information on the regenerative brake device, and transmits necessary information to the brake ECU 70 in response to a request from the brake ECU 70 as described above. The various information handled by the hybrid ECU 80 here includes a regenerative execution torque calculated from the counter electromotive force generated by the motor.

  As described above, the vehicle brake system 1 including the hydraulic brake device and the regenerative brake device according to the present embodiment is configured. In the vehicular brake system 1 configured as described above, when the control for inhaling the brake fluid from the inside of the M / C 13 is executed, that is, when the deterioration of the brake feeling may occur, Control is performed to prevent deterioration. For example, as an example of the control in which the brake fluid is sucked from the M / C 13, there is a process of switching from the regenerative braking force to the hydraulic braking force.

  When regenerative cooperative control is performed in the vehicle brake system 1 of the present embodiment, a regenerative braking force is generated when a braking force that generates a predetermined deceleration is generated by a regenerative braking force and a further deceleration is generated. The amount of braking force that is insufficient for power is generated by the hydraulic braking force based on the M / C pressure generated by depressing the brake pedal 11. The braking force for generating the predetermined deceleration is basically generated by the regenerative braking force, but the regenerative braking force that can be generated at that time varies depending on the situation of the motor 81 and the like. When a predetermined deceleration cannot be obtained with the regenerative braking force that can be generated or when it is desired to prioritize the hydraulic braking force over the regenerative braking force, the corresponding braking force is compensated by the hydraulic braking force based on the pump drive. . In such a case, since the brake fluid in the M / C 13 is sucked and supplied to the W / C 14, 15, 34, 35 side by the pump drive, the M / C pressure decreases and the pedal reaction force decreases. If the brake pedal 11 is sucked into the M / C 13 side, the brake feeling may be deteriorated.

  The above operation is also performed when switching from regenerative braking force to hydraulic braking force, so that the brake pedal 11 may be sucked into the M / C 13 side and the brake feeling may be deteriorated. In order to prevent this, at least one of the suction occurrence state where the suction of the brake pedal 11 is generated and the suction prediction state where the suction is expected to occur, the master reservoir through the M / C 13 is used. The brake fluid may be sucked from the 13e side.

  However, if the regenerative braking force is simply switched to the hydraulic braking force, the normal ports 13f and 13g and the regenerative port 13h are blocked by the master pistons 13a and 13b. The brake fluid cannot be sucked from the master reservoir 13e side through the inside.

  For this reason, in this embodiment, as control for preventing the deterioration of the brake feeling, the amount of brake fluid supplied from the M / C 13 to the W / C 14, 15, 34, 35 by the pump drive is more than the normal replacement. The master pistons 13a and 13b are caused to fall down by increasing the brake fluid supply increase control. As a result, the sealing force between the master pistons 13a, 13b and the inner wall surfaces of the chambers 13c, 13d is reduced, and the brake fluid can be sucked from the master reservoir 13e side through the M / C 13. This phenomenon will be described with reference to FIG.

  FIG. 3 is a cross-sectional view showing the inside of the M / C 13. First, since the master pistons 13a and 13b are not pushed before the brake pedal 11 is depressed, the normal ports 13f and 13g and the regenerative port 13h are opened as shown in FIG. Yes. Therefore, as indicated by the arrows in the figure, the brake fluid can be sucked from the master reservoir 13e through the ports 13f, 13g, and 13h. Even when the brake pedal 11 is depressed, the master reservoir 13e and the inside of the M / C 13 are in communication until the regenerative port 13h is blocked by the master piston 13a as shown in FIG. Brake fluid can be sucked from the master reservoir 13e side through the M / C 13.

  However, when the brake pedal 11 is further depressed, as shown in FIG. 3C, the regeneration port 13h is blocked by the master piston 13a, the master reservoir 13e and the inside of the M / C 13 are blocked, and the master reservoir 13e side It becomes impossible to inhale the brake fluid. However, if the amount of brake fluid supplied from the M / C 13 to the W / C 14, 15, 34, 35 by the pump drive is made larger than the normal replacement, as shown in FIG. The master pistons 13a and 13b are also sucked and fall down. Based on this falling, the outer peripheral seals of the master pistons 13a and 13b are separated from the inner wall surfaces of the respective chambers 13c and 13d, or the amount of deformation of the outer peripheral seal that has been elastically deformed is reduced, so that the seal between them is reduced. Power is reduced. Therefore, the brake fluid can be sucked from the master reservoir 13e through the M / C 13 beyond the seal portion.

  Thus, when the regenerative braking force is switched to the hydraulic braking force, the brake fluid is supplied from the master reservoir 13e even if the brake fluid in the M / C 13 is sucked by the pump drive. It is possible to suppress a decrease in the pedal reaction force due to a decrease. For this reason, it can suppress that the brake pedal 11 is inhaled by the M / C13 side, and can prevent the deterioration of a brake feeling.

  In order to increase the amount of brake fluid supplied from the M / C 13 to the W / C 14, 15, 34, 35 by driving the pump, compared to the normal replacement, for example, the unit time of the first and second differential pressure control valves 16, 36 What is necessary is just to enlarge the increase amount of the differential pressure per hit. In this way, since the differential pressure is increased from a state where the differential pressure is small, the brake fluid can be easily sucked and discharged by the pumps 19 and 39. For this reason, the ESC-ECU 3 controls the first and second differential pressure controls in at least one of the suction occurrence state where the brake pedal 11 is sucked and the predicted suction state where the suction is expected to occur. The master pistons 13a and 13b can be made to fall down by changing the differential pressure instruction value output to the valves 16 and 36 and increasing the amount of increase in the differential pressure per unit time as compared with normal switching.

  Specifically, the details of the brake fluid supply amount increase control that is performed during the process of switching from the regenerative braking force to the hydraulic braking force will be described. FIG. 4 is a flowchart showing details of the brake fluid supply amount increase control executed by the brake ECU 70. This process is executed every predetermined control cycle, for example, when the push start switch of the vehicle is turned on.

  First, in step 100, it is determined whether or not the vehicle speed Vs is equal to or less than the switching start vehicle speed V1 (for example, 14 km / h). In the switching process, for example, switching is performed from the time when the vehicle speed Vs reaches the switching start vehicle speed V1 so that the regenerative braking force is completely switched to the hydraulic braking force when the vehicle speed Vs reaches a predetermined speed before the vehicle stops. Has started. For this reason, it is confirmed whether or not it is in a state where the replacement is started by determining whether or not the vehicle speed Vs is equal to or lower than the replacement start vehicle speed V1 for starting the replacement.

  If an affirmative determination is made in this step, the routine proceeds to step 110, where it is determined whether or not the brake operation is in a holding state. For example, this determination is performed based on the stroke value St obtained from the detection signal of the stroke sensor 11a. Specifically, the absolute value | St (n) −St (n−1) | of the difference between the stroke value St (n) of the current control cycle and the stroke value St (n−1) of the previous control cycle is Whether or not the brake operation is in the holding state is determined by determining whether or not the stroke value St is less than the threshold value St1 that is assumed to be unchanged.

  If the determination in step 110 is affirmative, the process proceeds to step 120 to determine whether a replacement process is being performed. In the replacement process, since the regenerative braking force is replaced with the hydraulic braking force, the regenerative execution torque Tr gradually decreases. Therefore, for example, the regeneration execution torque Tr transmitted from the hybrid ECU 80 is confirmed, and the difference Tr (n) between the regeneration execution torque Tr (n) of the current control cycle and the regeneration execution torque Tr (n−1) of the previous control cycle. ) −Tr (n−1) is determined as to whether or not the replacement process is being performed by determining whether or not it is less than 0. Note that, during the replacement process, the brake fluid in the M / C 13 is supplied to the W / C 14, 15, 34, 35 by the control of the first and second differential pressure control valves 16, 36 and the pumps 19, 39. It is. For this reason, the determination that the replacement process is in progress is made by applying the brake fluid in the M / C 13 to the W / C 14, 15, 34, 35 under the control of the first and second differential pressure control valves 16, 36 and the pumps 19, 39. This means that it is determined that it is in a state of being supplied to

  If an affirmative determination is also made in this step, the routine further proceeds to step 130, where it is determined whether or not the M / C pressure Pm is equal to or lower than a predetermined pressure Pm1. The predetermined pressure Pm1 is a reference value indicating that the M / C pressure has decreased to an extent that the suction of the brake pedal 11 is expected to occur, and is set to 0.01 Mpa, for example. Brake fluid supply increase control may be performed when the suction has occurred, but when the suction is predicted to occur, the brake can be braked earlier. Generation | occurrence | production of the suction of the pedal 11 can be suppressed. Therefore, if an affirmative determination is made even in this step, the brake operation is maintained during the replacement, and the brake pedal 11 can be sucked in as the M / C pressure decreases. From step 140, the piston tilt control execution flag for turning the master pistons 13a and 13b down is turned on.

  Then, the process proceeds to step 150, and it is determined whether or not the predetermined time C1 is still before the piston tilting control execution flag is turned on. The predetermined time C1 is a time required for the master pistons 13a and 13b to fall down. Therefore, if the predetermined time C1 has not elapsed after the piston tilt control execution flag is turned on, the master pistons 13a and 13b are still tilted even if the processing for causing the master pistons 13a and 13b to fall is started. It will not be reached. Therefore, if an affirmative determination is made in this step, the process proceeds to step 160 in order to execute a process for causing the master pistons 13a and 13b to fall down (or continue the execution of the process).

  In step 160, it is determined whether or not the vehicle speed Vs is higher than the replacement end vehicle speed V2 (for example, 7 km / h). If the determination is affirmative before the end of replacement, the process proceeds to step 170 and the master piston 13a. , 13b is executed. As described above, in the switching process, for example, when the vehicle speed Vs reaches a predetermined speed before the vehicle stops, that is, when the switching end vehicle speed V2 is reached, all the regenerative braking force is switched to the hydraulic braking force. If the vehicle speed Vs is higher than the vehicle speed V2, the vehicle is being replaced or being replaced. Therefore, if an affirmative determination is made in step 160, the process proceeds to step 170, where the piston inversion control differential pressure instruction value B (n) is set as the differential pressure instruction value of the first and second differential pressure control valves 16 and 36. Specifically, the master pistons 13a and 13b in the state where the differential pressure command value B (n) of the current control cycle is equal to the differential pressure command value B (n-1) of the previous control cycle and the M / C pressure Pm is 0 Pa. Is calculated from the following equation using a design value α set so that the brake fluid supply amount falls.

(Equation 1) B (n) = B (n−1) + | B (n−1) −B (n) | × α
When the process of step 170 is executed for the first time, B (n−1) and B (n) on the right side are respectively differential pressures for normal control set at the time of normal replacement in step 180 described later. The differential pressure command value of the previous control cycle of the command value and the differential pressure command value of the current control cycle are used. When the execution of step 170 is performed for the second time or later, B (n−1) and B (n) on the right side include the differential pressure command value of the previous control cycle of the differential pressure command value for piston tilt control. And the differential pressure instruction value of the current control cycle is used.

  In this way, by setting the piston tilt control differential pressure command value B (n), the amount of increase in the differential pressure of the first and second differential pressure control valves 16 and 36 is larger than that during normal replacement. Can be. For this reason, it becomes possible to increase the supply amount of the instantaneous brake fluid more than at the time of normal replacement, and the master pistons 13a and 13b can be brought down. Accordingly, when the regenerative braking force is switched to the hydraulic braking force, the brake fluid is supplied from the master reservoir 13e even if the brake fluid in the M / C 13 is sucked by the pump drive, so that the M / C pressure is reduced. It can suppress that it falls and pedal reaction force falls. For this reason, it can suppress that the brake pedal 11 is inhaled by the M / C13 side, and can prevent the deterioration of a brake feeling.

  On the other hand, if a negative determination is made in steps 100 to 130, 150, it is not the replacement process, the suction of the brake pedal 11 is considered not to occur, or after execution of the piston tilting control in the replacement process. For this reason, the process proceeds to step 180, where a normal control differential pressure command value B (n) that is not for piston tilt control is set. Thus, for example, during the replacement process, the differential pressure instruction value B (n) that is normally set at the time of replacement, that is, the differential pressure instruction value B (n) is higher than the differential pressure instruction value B (n) for piston tilt control. The amount of change is set small.

  On the other hand, if a negative determination is made in step 160, since the replacement has been completed, the routine proceeds to step 190, the piston fall control execution flag is turned off, and then the routine proceeds to step 180 where the normal control differential pressure command value B (N) is set. As described above, the brake fluid supply amount increase control is executed.

  5 and 6 are time charts when the brake fluid supply amount increase control as described above is executed, and the brake operation is performed to such an extent that a relatively high deceleration (high G) is generated. And a case where the brake operation is performed to such an extent that a relatively low deceleration (low G) is generated. Specifically, the example of FIG. 5 shows a case where the deceleration generated with the target braking force corresponding to the stroke value St is sufficiently larger than the predetermined deceleration generated with the maximum regenerative braking force. . The example of FIG. 6 shows a case where the deceleration generated with the target braking force corresponding to the stroke value St is slightly larger than the predetermined deceleration generated with the maximum regenerative braking force.

  As shown in FIGS. 5 and 6, during the period from the time T1 when the brake operation starts to the time when the regenerative braking force is generated, the differential pressure of the first and second differential pressure control valves 16 and 36 is increased. The instruction value is set to a value that generates a target braking force corresponding to the stroke value St of the brake pedal 11. As the pump is driven, the brake fluid in the M / C 13 is sucked and discharged toward the W / Cs 14, 15, 34, and 35 to generate W / C pressure. In this way, the target braking force is generated by the hydraulic braking force driven by the pump.

  Subsequently, at time T2 when a predetermined time has elapsed from the start of the brake operation, the regenerative braking force is generated, and the hydraulic braking force generated by driving the pump is replaced with the regenerative braking force. Specifically, the differential pressure command value B (n) of the first and second differential pressure control valves 16 and 36 is decreased in accordance with the gradient in which the regenerative braking force can be increased, so that the total of the hydraulic braking force and the regenerative braking force is reduced. The hydraulic braking force is replaced with the regenerative braking force while making the braking force of the above coincide with the target braking force.

  Further, when the brake pedal 11 is depressed so that the deceleration generated by the target braking force corresponding to the stroke value St at time T3 exceeds the deceleration generated by the maximum regenerative braking force, the regenerative port 13h is blocked. M / C pressure Pm is generated. Thus, in addition to the hydraulic braking force and regenerative braking force driven by the pump, a hydraulic braking force based on the M / C pressure Pm generated by the depression of the brake pedal 11 is generated by the hydraulic brake device, and these total braking forces are generated. A target braking force is generated by.

  Thereafter, when all of the hydraulic braking force based on the pump drive is replaced with the regenerative braking force at time T4, the differential pressure instruction values of the first and second differential pressure control valves 16 and 36 become 0, and further, the vehicle speed at time T5. When Vs reaches the replacement start vehicle speed V1, a replacement process is performed in which the regenerative braking force is replaced with the hydraulic braking force based on the pump drive.

  At this time, since the normal ports 13f and 13g and the regenerative port 13h are blocked by the depression of the brake pedal 11 and the M / C pressure Pm is generated, the brake fluid is supplied from the master reservoir 13e. It is in a state that is not broken. For this reason, if brake fluid is sucked from the M / C 13 by driving the pump, the brake pedal 11 may be sucked into the M / C 13 side.

  However, when the M / C pressure Pm generated during the replacement process falls below the predetermined pressure Pm1, the piston tilt control execution flag is turned on, and the differential pressure instructions of the first and second differential pressure control valves 16, 36 are given. Since the value is set to the piston tilt control differential pressure command value B (n), the amount of change in the differential pressure of the first and second differential pressure control valves 16 and 36 is greater than that at the time of normal replacement indicated by the broken line in the figure. Can also be larger. Therefore, the brake pedal 11 can be prevented from being sucked into the M / C 13 side, and deterioration of the brake feeling can be prevented.

  Although the generated M / C pressure Pm is different in each example shown in FIGS. 5 and 6, as shown in FIG. 5, when a certain high M / C pressure Pm is generated, Even when the suction of the brake pedal 11 can occur during the replacement process, as shown in FIG. 6, when the M / C pressure Pm is low and the suction of the brake pedal 11 can occur at the initial stage of the replacement process. In this case, the above effect can be obtained.

  As described above, in the vehicle brake system 1 of the present embodiment, when the ports 13f, 13g, and 13h are closed, the brake fluid is sucked from the M / C 13 by the pump drive, and the W / C 14, 15, When pressurizing 34 and 35, brake fluid supply amount increase control is performed. That is, in at least one of the suction occurrence state where the suction of the brake pedal 11 is generated or the predicted suction state where the suction is expected to occur, the brake fluid is compared with the case where the state is not these states. The supply amount is increased. As a result, the master pistons 13a and 13b are caused to fall down, and the sealing force between the master pistons 13a and 13b and the inner wall surfaces of the chambers 13c and 13d can be reduced. Brake fluid can be inhaled. For this reason, it can suppress that the brake pedal 11 is inhaled by the M / C13 side, and can prevent the deterioration of a brake feeling.

  Note that, when the brake fluid supply amount increase control is performed, the hydraulic braking force due to the pump drive instantaneously increases, so that the total braking force may exceed the target braking force. However, when switching the regenerative braking force to the hydraulic braking force by the pump drive, it is a situation where the vehicle wants to stop by generating a deceleration, and since the vehicle speed is already low, the hydraulic pressure control by the pump drive is instantaneous. Even if the power increases, the vehicle behavior does not fluctuate greatly and the driver does not feel uncomfortable.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, when the piston tilt control differential pressure command value B (n) is set based on Formula 1 as in the first embodiment, the differential pressure command value B (n− of the previous control cycle is set for each control cycle. 1) and the value obtained by multiplying the absolute value of the difference between the differential pressure command value B (n) in the current control cycle by α is added, so that the differential pressure command value B (n) for normal control is initially added. Although the increase amount of the differential pressure command value B (n) for piston tilt control with respect to is small, the increase amount gradually increases exponentially every control cycle. However, this shows an example in which the amount of change in the differential pressure of the first and second differential pressure control valves 16 and 36 is larger than that during normal replacement. Other methods such as increasing a certain amount from the value B (n) may be used. However, the differential pressure of the first and second differential pressure control valves 16 and 36 can be increased by gradually increasing the piston tilting control differential pressure command value B (n) for each control cycle as in the first embodiment. The amount of change from the regenerative braking force to the hydraulic braking force can be prevented from increasing suddenly, while the amount of change in the value is larger than that during normal replacement.

  Also, as in the first embodiment, when the predetermined time C1 has elapsed after the piston collapse flag is turned on, the differential pressure command value B (n) for normal control is restored. The pressure command value B (n) is suddenly returned to the normal control differential pressure command value B (n). However, this is merely an example of returning from the piston tilt control differential pressure command value B (n) to the normal control differential pressure command value B (n), and other methods may be used. For example, the normal pressure differential command value B (n) may gradually approach the piston tilt control differential pressure command value B (n).

  Further, in the first embodiment, as the brake fluid supply amount increase control, the differential pressure command value of the first and second differential pressure control valves 16 and 36 is set to the piston tilt control differential pressure command value B (n). Thus, the case where the value is larger than the normal control differential pressure command value B (n) is taken as an example. However, this is merely an example of a mode in which the amount of brake fluid supplied from the pump driven M / C 13 to the W / C 14, 15, 34, 35 is larger than the normal replacement. It is good as a method. For example, the supply amount of the brake fluid may be made larger than the normal replacement by instantaneously increasing the rotation speed of the pumps 19 and 39.

  In the first embodiment, the regenerative port 13h is provided so that the M / C pressure is not generated until the braking force corresponding to the maximum regenerative braking force is generated by the regenerative braking force or the hydraulic braking force by the pump drive. It was set as the form to do. However, the regenerative port 13h is not necessarily provided, and the M / C pressure may be generated before the braking force corresponding to the maximum regenerative braking force is generated by the regenerative braking force or the hydraulic braking force by the pump drive. .

  In the first embodiment, the ESC-ECU 70 and the hybrid ECU 80 correspond to the braking force control means of the present invention. The steps shown in FIG. 4 correspond to means for executing various processes. For example, the part that executes the processing of steps 100 to 170 corresponds to the brake fluid supply amount control means.

   DESCRIPTION OF SYMBOLS 1 ... Vehicle brake system, 11 ... Brake pedal, 13 ... M / C, 14, 15, 34, 35 ... W / C, 16, 36 ... 1st, 2nd differential pressure control valve, 19, 39 ... Pump, DESCRIPTION OF SYMBOLS 50 ... Actuator for brake fluid pressure control, 51 ... M / C pressure sensor, 60 ... Motor, 70 ... Brake ECU, 80 ... Hybrid ECU, 81 ... Motor, 82 ... Inverter, 83 ... Battery

Claims (4)

A master cylinder that generates a master cylinder pressure corresponding to the amount of brake operation when the driver operates the brake operation member (11) and receives brake fluid from the master reservoir (13e) through the ports (13f, 13g, 13h) (13) and a wheel cylinder (14, 15, 34, 35) that generates a hydraulic braking force for each wheel (FL to RR) by applying a wheel cylinder pressure based on the master cylinder pressure; A differential pressure control valve (16, 36) that is provided in a hydraulic pressure path between the master cylinder and the wheel cylinder and controls a differential pressure between the hydraulic pressure on the master cylinder side and the hydraulic pressure on the wheel cylinder side; A pump that discharges the brake fluid of the master cylinder to the wheel cylinder side from the differential pressure control valve of the fluid pressure path And 19 and 39) has a hydraulic brake device that generates a hydraulic braking force based on the wheel cylinder pressure,
A regenerative braking device (81-83) that generates a regenerative braking force by applying a resistance force based on power generation to the wheel by generating power based on the rotational force of the wheel;
By performing cooperative control of the hydraulic brake device and the regenerative brake device, a braking force control means (70, 70) that controls the hydraulic braking force generated by the hydraulic brake device and the regenerative braking force generated by the regenerative brake device. 80)
When the brake fluid in the master cylinder is supplied into the wheel cylinder by the control of at least one of the pump and the differential pressure control valve by the braking force control means in a state where the port is closed, When the brake fluid supply is at least one of a suction occurrence state where the brake operation member is sucked into the master cylinder side and a suction prediction state where the suction is expected to occur Furthermore, compared with the case where it is not the said state, the brake fluid supply amount which increases the supply amount of the brake fluid from the said master cylinder per unit time to the said wheel cylinder so that a master piston (13a, 13b) may fall down. Brake fluid supply amount control means (100 to 170) for executing increase control; Brake system for a vehicle, characterized by that. The braking force control means includes
During braking, the hydraulic braking device generates the regenerative braking force generated by the regenerative braking device based on the driving of the pump by increasing the hydraulic braking force in response to the decrease in the regenerative braking force. Execute the replacement process to replace the hydraulic braking force
The brake fluid supply amount control means supplies brake fluid in the master cylinder into the wheel cylinder by controlling at least one of the differential pressure control valve and the pump when the replacement process is being performed. The vehicle brake system according to claim 1, wherein the vehicle brake system is determined.   3. The vehicle according to claim 1, wherein the brake fluid supply amount control means increases the increase amount per unit time of the differential pressure by the differential pressure control valve in the brake fluid supply amount increase control. Brake system.   The said brake fluid supply amount control means determines that it is in the said suction | emission prediction state, when the said master cylinder pressure is below the said predetermined pressure, The one of Claims 1 thru | or 3 characterized by the above-mentioned. Vehicle brake system.

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